Printing press environments are potentially hazardous environments. The operation of a printing press may generate hazardous contaminants and other byproducts which are released into the air surrounding the printing press. These contaminants and other byproducts need to be controlled to ensure a safe working environment and to meet federal regulations which mandate the amount of impurities that may be in the air. Toluene is an example of an impurity which may be found in an enclosed environment for a printing press. Toluene is an explosive chemical. Concentration levels of toluene in the air surrounding the printing press need to be closely monitored and controlled.
Present methods to control impurity levels within the printing press environment use a constant exhaust fan speed. The speed of the exhaust fan is chosen to prevent impurity levels from reaching worst case conditions (e.g., an upper threshold of impurity levels). However, the impurity levels in the printing press environment fluctuate due to different stages of the printing process and from different materials that are being printed. Since the impurity levels fluctuate, there are periods of time when the impurity levels are far below the upper threshold and therefore do not require the exhaust fan speed to be equal to the speed required to prevent the worst case condition. The lack of exhaust fan speed control results in a first source of wasted energy.
Typically, a constant static pressure is also maintained in the enclosed environment for a printing press to assist with the containment of the impurities produced by the printing press. The constant static pressure is maintained by an intake fan with a constant speed. The total volume of air supplied to the environment by the intake fan is equal to the total volume of air exhausted by the exhaust fan. Again, due to the fluctuations in the impurity levels within the printing press environment and the constant exhaust fan speed, the intake fan is not being used efficiently. This results in a second source of wasted energy.
In addition to a constant static pressure, a constant temperature is typically maintained in the enclosed environment for a printing press. To maintain a constant temperature within the enclosed environment for a printing press, the air supplied by the intake fan needs to be conditioned (e.g., heated or cooled). Because the speed of the intake fan is constant, a larger volume of air is being supplied to the enclosed environment than would be necessary if the exhaust fan speed (and therefore the intake fan speed) were not constant. This leads to a greater volume of air that needs to be conditioned by the heating and cooling units. This results in a third source of wasted energy.